Opens the encrypted PDF file held by stream, from its current position, with credentials.
public PdfDocument Open(Stream stream, PdfCredentials credentials)
The stream. It is not disposed; keep it open and unchanged until the document is disposed.
The credentials, such as a PdfPassword; they override those set on the options.
ISO 32000-2 §7.5 and §7.6. For an unencrypted file the credentials are ignored.